93 Questions
In which type of vibration do the particles of the shaft or disc move parallel to the axis of the shaft?
Longitudinal vibrations
What type of vibrations occur when the particles of the shaft or disc move in a circle about the axis of the shaft?
Torsional vibrations
When the particles of the shaft or disc move approximately perpendicular to the axis of the shaft, what type of vibrations are induced?
Transverse vibrations
Which type of vibration causes the shaft to be twisted and untwisted alternately?
Torsional vibrations
If a system executes longitudinal vibrations, what is happening to the shaft?
It is elongated and shortened alternately
What type of stresses are induced in the shaft during transverse vibrations?
Bending stresses
What term is used to describe the speed at which the shaft runs so that the additional deflection of the shaft from the axis of rotation becomes infinite?
Critical or whirling speed
What factor contributes to the bending of a shaft carrying gears or pulleys?
Eccentricity and speed
In a single rotor system, where is the node located?
At point N
What is the force resisting the deflection 'y' in a rotating shaft with a rotor?
Stiffness of the shaft
What causes a rotating shaft to deflect due to centrifugal force?
Centrifugal force acting through G
What does the term 'critical or whirling speed' correspond to in terms of natural frequency?
Natural frequency divided by 2
In a rotating shaft with a rotor, what happens when the circular frequency 'n' is equal to 'c'?
The value of y becomes infinite
What determines the natural frequency for Rotor A in a two-rotor system?
Mass moment of inertia of rotor A
What must be true for torsional vibrations to occur in a two-rotor system?
The two rotors must move in opposite directions and have the same frequency
What affects the natural frequency in a three-rotor system?
Mass moment of inertia of rotor C
What type of vibrations occur when the particles of the shaft or disc move in a circle about the axis of the shaft?
Torsional vibrations
During transverse vibrations, what type of stresses are induced in the shaft?
Bending stresses
In which type of vibration do the shaft particles move parallel to the axis of the shaft?
Longitudinal vibrations
What occurs during transverse vibrations in terms of shaft behavior?
The shaft is straight and bent alternately
What type of vibrations cause tensile and compressive stresses to be induced alternately in the shaft?
Transverse vibrations
What is the term for vibrations where the shaft is twisted and untwisted alternately?
Circumferential vibrations
What process does the refrigerant undergo in the condenser?
Condensing process
What happens to the refrigerant as it passes through the expansion valve?
It expands
During which process does the liquid refrigerant evaporate?
Expansion process
What is the pressure at point 4 in the system?
$p_1$
What does the refrigerant give to the surrounding condensing medium in the condenser?
Latent heat
What is the speed at which the additional deflection of the shaft becomes infinite known as?
Critical or whirling speed
In a rotating shaft with gear or pulleys, what force causes the shaft to bend?
Centrifugal force
What happens to the value of deflection 'y' when the circular frequency 'n' equals 'c'?
It becomes infinite
What is the unit for critical or whirling speed?
Revolutions per second
In a two-rotor system, when do torsional vibrations occur?
When both rotors move in opposite directions
What factor determines the bending of a shaft carrying gears or pulleys?
Speed of rotation
Where does the node lie in a two-rotor system during torsional vibrations?
At the fixed end of the shaft
'Free Torsional Vibrations' occur in a system where:
The rotor is fixed at one end of the shaft
'Modulus of rigidity' represents the resistance of a shaft to:
Torsional vibrations
'Efficiencies of both living and non-living beings depend to a great extent on the physical environment.' implies that:
'Efficiency' varies based on environmental factors
What is the machinery known as that performs the operation of increasing the temperature inside a car?
Heat pump
In a refrigeration system, what is the direction of heat flow?
From a lower temperature space to a higher temperature environment
What does air conditioning involve controlling in addition to temperature?
Temperature, humidity, cleanliness, and air motion
Why is controlling temperature alone not sufficient for comfort according to the text?
Humidity plays a crucial role in comfort
Which city is used as an example in the text to explain the importance of controlling both temperature and humidity for comfort?
Shillong
What additional parameter besides temperature and humidity is mentioned as essential for comfort in the text?
Air motion
What must be done to pump heat into or out of a space according to the text?
Perform external work using a mechanical device
What role does a heat pump play in controlling the temperature of a space?
Pumping heat in or out as needed
'Heat flows from a body at a higher temperature to a body at a lower temperature' is an example of what concept?
'Water flows from a higher level to a lower level' principle
'Heat is pumped out from a lower temperature space to a higher temperature environment' is characteristic of which system?
'Refrigeration system' operation
What was the most significant development in refrigeration systems in the 1930s?
Invention of chlorofluorocarbon refrigerants
What is the purpose of an evaporator in a refrigeration system?
To evaporate liquid ammonia
When was the first two-stage modern compressor developed?
1915
What is the primary function of an absorber in a vapor-absorption refrigeration system?
To absorb weak aqua ammonia
Which development occurred when the refrigeration industry had stagnated on NH3 and SO2 as refrigerants?
Invention of chlorofluorocarbon refrigerants
What is the purpose of a generator in a vapor-absorption refrigeration system?
To separate ammonia vapor
What is the role of a condenser in a refrigeration system?
To condense ammonia vapor
When did significant diversification in refrigeration systems begin to occur?
'Round 1920
What is the primary purpose of air conditioning in buildings?
Providing comfortable conditions for people year-round
What are the ventilation requirements for hospitals and medical buildings?
Use of 100 percent outdoor air and humidity limits
In industrial air conditioning, what is the purpose of spot heating?
Warming a confined zone where a worker is located
Why is control of humidity crucial in the printing industry?
To prevent static electricity issues
What is the primary role of air conditioning in precision parts manufacturing?
Maintain uniform temperature, humidity, and filter air
Why is air conditioning essential in computer rooms?
To control temperature, humidity, and cleanliness
What major contributor to cooling load is found in vehicles that are air conditioned?
Heat from solar radiation
Why is refrigeration important for food storage and distribution?
To extend the storage life of perishable foods
What special temperature condition is required in the photographic-products industry?
-40°C for certain equipment testing
What role does air conditioning play in extending the life of perishable foods in food storage?
Extending the storage life by maintaining low temperatures
What is the main purpose of refrigeration and air conditioning?
To remove heat from spaces to provide comfort
Why is it necessary to have control over the environment?
To enable living beings to perform better
How does refrigeration work in preserving perishable food items?
By slowing down molecular motion and bacteria growth
In refrigeration, where is the unwanted heat removed from a space transferred to?
Transferred to the surrounding environment
How does refrigeration contribute to air conditioning in cars?
By transferring heat from inside the car to the surroundings
What happens to the temperature inside a refrigerator when unwanted heat is removed?
The temperature decreases
Why is it important for a car's interior to have a lower temperature than outside during summers?
To provide comfort during a hot drive
What is the volume relationship between a car's interior and its surrounding environment during air conditioning?
The volume of the car is much less than its surroundings
Why is refrigeration essential for preserving perishable food items?
To slow down bacterial growth and molecular motion.
Why would it be uncomfortable to drive in a car without air conditioning during an Indian summer in Delhi or Kanpur?
Due to high external temperatures.
What is the standard unit of refrigeration?
Ton refrigeration
Which substance is commonly used as a refrigerant in a vapour compression cycle?
Ammonia (NH3)
What role does the compressor play in a simple vapour compression refrigeration system?
Compressing the vapour refrigerant
Where is the condensed liquid refrigerant stored in the system?
Receiver
What is the function of the expansion valve in a vapour compression system?
Reducing the pressure and temperature of the refrigerant
During which process of the theoretical vapour compression cycle does isentropic compression occur?
Compression Process
What happens to the pressure and temperature of the vapour refrigerant during isentropic compression?
Pressure increases, temperature increases
Which component of a vapour compression system cools and condenses the high-pressure vapour refrigerant?
Condenser
What absorbs latent heat from the solution in a simple vapour compression system?
Evaporator
Where is the liquid-vapour refrigerant evaporated and changed into vapour refrigerant at low pressure and temperature in a simple vapour compression system?
Evaporator
What distinguishes the summer air conditioning system from the winter air conditioning system?
Summer air conditioning cools the space and removes extra moisture, while winter air conditioning heats the space and adds moisture.
How is industrial air conditioning different from comfort air conditioning?
Industrial air conditioning includes air conditioning of printing plants and computer rooms, while comfort air conditioning deals with spaces like homes and offices.
What was one method used to produce ice around 4000 years ago?
Keeping water in porous pots outside during the night
Who obtained the first British Patent related to refrigeration in 1790?
Thomas Hariss and John Long
Which pioneer developed a hand-operated refrigeration system using ether as the working fluid?
Jacob Perkins
What was the purpose of Dr. John Gorrie's cold air machine patented in 1851?
To cure people suffering from high fever
Instead of air or ether, what substance did Dr. James Harrison use in his refrigeration machine for brewery?
Sulfuric ether
In which century were East Indians producing ice by dissolving salt in water to cool beverages?
4th century A.D.
Test your knowledge on the three important types of free vibrations: Longitudinal, Transverse, and Torsional vibrations. This quiz explores scenarios of weightless constraints with heavy discs experiencing different vibration types.
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